1. Field of the Invention
The present invention relates to systems for filtering contaminants from fluids such as drain water and stormwater. More particularly, the present invention relates to a filter system and related method for removing contaminants from a fluid stream by forcing upward and/or radial flow of the fluid through the filter means.
2. Description of the Prior Art
Fluid transfer systems have been and will remain an important aspect of municipal services and commercial facilities management. The protection of ground water and natural bodies of water requires systems for diverting and/or treating water that contacts roadways, parking lots, and other man made structures. If such diversion or treatment systems are not provided, particulate and contaminants located on or forming part of such structures may be carried by drain water or stormwater to the natural water bodies and contaminate them. Local, state and federal laws and rules require municipalities, businesses, and in some instances, private entities, to establish means to reduce particulate and dissolved pollutant levels permissibly transferred to natural bodies of water from property under their control. Particular requirements may vary from jurisdiction to jurisdiction, but all are likely to become more stringent.
Previously, municipal water transfer and treatment facilities provided the only mechanism for diverting contaminated water away from natural bodies of water, either for holding or treatment for subsequent transfer to natural settings. In general, that process involved, and continues to involve, the establishment of a system of drains, such as in a parking lot or at a street curb, by which water enters a system of pipe conduits. Eventually, the water received from the drains reaches either a final outlet destination or is directed to a treatment system for contaminant removal. For purposes of the description of the present invention, “contaminated water” is to be understood to mean any water including floating particulate, such as Styrofoam™ containers and oil, for example; non-floating particulate, such as sand and silt, for example; and suspended and dissolved contaminants, such as fine solids, oil, grease, organic contaminants including fertilizers, herbicides, and pesticides, and metals, for example.
Land development produces increased quantities of drain water and stormwater runoff, resulting in increased strain on existing water transfer and treatment infrastructure and an increased likelihood of natural water contamination. In an effort to reduce the impact of development on natural resources and municipal services, initial upstream fluid treatment has become a requirement in many land development, restoration and repair projects. That is, requirements in various forms have been established to ensure that before contaminated water enters the municipal water transfer and/or treatment system or a natural body of water, it must be treated in a manner that reduces the level of contaminants entering the municipal system or the natural body of water. Therefore, most new land development plans and upgrades to existing paved surfaces involve the insertion of a preliminary separation system, generally for connection to the municipal water-handling infrastructure. In other cases, the outflow from the separation system may be transferred directly to a natural body of water.
Any preliminary separation system must be designed with the capability to receive fluid flowing in at a wide range of rates. For example, a mild rainfall resulting in rain accumulation of less than 0.25 inches over a span of 24 hours produces a relatively low flow rate through the system. On the other hand, for example, a torrential rainfall resulting in rain accumulation of more than two inches over a span of three hours produces relatively high flow rates through the system. It is desirable, then, to have a separation system capable of handling variable fluid flow rates with reduced likelihood of backup and flooding of the surface above.
In addition to having a reasonable fluid flow throughput capacity, the separation system must be capable of performing the separation function for which it is intended. Relatively large floating particulate and relatively heavy non-floating particulate have been, and are, handled in a number of ways. For example, biofiltration swales, settling ponds, fluid/particle density separators, mechanical separators and media absorbers and filters are employed to remove such types of contaminants. Swales and settling ponds take up significant real estate and are therefore generally not particularly desirable in many settings. The separators require less space to operate, but are relatively costly and require considerable servicing on a regular basis. Existing absorbers and filter mechanisms may be effective at removing specified contaminants; however, they tend to do so at the expense of flow through rates. That is, the filtration efficiency is relatively low in comparison to the required water flow through desired. That may be acceptable under relatively low flow rates; but not so under relatively high flow rates. More efficient systems such as the one described in U.S. Pat. No. 5,759,415 issued to Adams on Jun. 2, 1998, assigned to Vortechnics, Inc. and entitled METHOD AND APPARATUS FOR SEPARATING FLOATING AND NON-FLOATING PARTICULATE FROM RAINWATER DRAINAGE, have been developed and employed to treat water in areas where treatment space is limited. However, regulations regarding the removal of suspended/fine solid particulates and/or dissolved and un-dissolved chemical contaminants have resulted in the need for supplemental removal arrangements.
There is an increasing need and requirement for separation systems associated with drain water and stormwater introduction to municipal water handling systems and natural bodies of water to remove a substantial portion of all forms of contaminants entering the municipal systems or bodies of water at a point closer to the source. However, it is important that the separation systems not be prohibitively expensive in order to ensure that meeting those needs and requirements is feasible. It is also of importance that such separation systems are relatively easy to maintain. It is becoming increasingly important that these separation systems include means for removing suspended solids and/or chemical contaminants, but without sacrificing the other desired characteristics. Fluid filter systems that are configured to allow for loading of the filter by all floating and nonfloating particulates require maintenance over relatively short intervals. In subsequent fluid treatment cycles, contaminants that remain caked-on the filter surface reduce fluid flow through effectiveness and must therefore be removed relatively frequently. In addition, wet, caked filters are very heavy and therefore require the use of assistive equipment, such as cranes, when they are to be removed for maintenance.
Therefore, what is needed is a separation system and related method for removing suspended and/or chemical contaminants from a fluid stream as part of a separation system that may or may not be part of a larger fluid handling system, wherein the separation system is effective in accommodating varied fluid flow rates. What is also needed is such a separation system that is cost effective and configured for ease of maintenance, including, for example, addressing the limitations of contaminant retention on the filter and filter device weight that shorten maintenance cycles and increase maintenance difficulty. Further, what is needed is such a separation system that includes a filter system capable of removing identified contaminants with minimal impact on fluid flow rates.